.\"
.\" SPDX-License-Identifer: BSD-3-Clause
.\"
.\" Copyright (c) 1995, 1996, 1997, 1998, 2000
.\" 	Justin T. Gibbs.  All rights reserved.
.\" Copyright (c) 2002
.\"	Scott Long.  All rights reserved.
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.\" modification, are permitted provided that the following conditions
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.Dd September 29, 2025
.Dt AHD 4
.Os
.Sh NAME
.Nm ahd
.Nd Adaptec PCI/PCI-X Ultra320 SCSI host adapter driver
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device pci"
.Cd "device scbus"
.Cd "device ahd"
.Pp
To compile in debugging code:
.Cd options AHD_DEBUG
.Cd options AHD_DEBUG_OPTS=<bitmask of options>
.Cd options AHD_REG_PRETTY_PRINT
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
ahd_load="YES"
.Ed
.Sh DESCRIPTION
This driver provides access to the
.Tn SCSI
bus(es) connected to Adaptec
.Tn AIC79xx
host adapter chips.
.Pp
Driver features include support for narrow and wide busses,
fast, ultra, ultra2, ultra160, and ultra320 synchronous transfers,
packetized transfers, tagged queueing, 512 SCB's, and target mode.
.Pp
The
.Dv AHD_DEBUG_OPTS
option is used to control which diagnostic messages are printed to the
console when
.Dv AHD_DEBUG
is enabled.
Logically OR the following bits together:
.Bl -column -offset indent Value Function
.Em "Value	Function"
0x0001	Show miscellaneous information
0x0002	Show sense data
0x0004	Show Serial EEPROM contents
0x0008	Show bus termination settings
0x0010	Show host memory usage
0x0020	Show SCSI protocol messages
0x0040	Show mode pointer of the chip register window
0x0080	Show selection timeouts
0x0100	Show FIFO usage messages
0x0200	Show Queue Full status
0x0400	Show SCB queue status
0x0800	Show inbound packet information
0x1000	Show S/G list information
0x2000	Enable extra diagnostic code in the firmware
.El
.Pp
The
.Dv AHD_REG_PRETTY_PRINT
option compiles in support for human-readable bit definitions for each register
that is printed by the debugging code.
However, it also bloats the compiled
size of the driver by approximately 215KB.
.Pp
Per target configuration performed in the
.Tn SCSI-Select
menu, accessible at boot,
is honored by this driver.
This includes synchronous/asynchronous transfers,
maximum synchronous negotiation rate,
wide transfers,
disconnection,
and the host adapter's
.Tn SCSI
ID.
.Sh CONFIGURATION OPTIONS
To statically configure one or more controllers to assume the target role:
.Pp
.Cd options AHD_TMODE_ENABLE <bitmask of units>
.Bd -ragged -offset indent
The value assigned to this option should be a bitmap of all units where target
mode is desired. For example, a value of 0x25, would enable target mode on
units 0, 2, and 5. A value of 0x8a enables it for units 1, 3, and 7.
.Pp
Note that controllers can be dynamically configured through a device hint
documented below.

.Ed
.Sh BOOT OPTIONS
The following options are switchable by setting values in
.Pa /boot/device.hints .
.Pp
They are:
.Bl -tag -width indent
.It Va hint.ahd. Ns Ar N Ns Va .tmode_enable
A hint to define whether the SCSI target mode is enabled (0 -- disabled, 1 -- enabled).
.El
.Sh HARDWARE
The
.Nm
driver supports the following PCI/PCI-X parallel SCSI controllers:
.Pp
.Bl -bullet -compact
.It
Adaptec
.Tn AIC7901
host adapter chip
.It
Adaptec
.Tn AIC7901A
host adapter chip
.It
Adaptec
.Tn AIC7902
host adapter chip
.It
Adaptec
.Tn 29320
host adapter
.It
Adaptec
.Tn 39320
host adapter
.It
Many motherboards with on-board
.Tn SCSI
support
.El
.Sh SEE ALSO
.Xr ahc 4 ,
.Xr cd 4 ,
.Xr da 4 ,
.Xr sa 4 ,
.Xr scsi 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 4.7 .
.Sh AUTHORS
The
.Nm
driver, the
.Tn AIC7xxx
sequencer-code assembler,
and the firmware running on the aic79xx chips was written by
.An Justin T. Gibbs .
This manual page is based on the
.Xr ahc 4
manual page.
.Sh BUGS
The current generation of 79xx chips do not support target mode in Ultra320
mode.
Target mode in general has not been well tested in this driver.
